The following description of the background of the invention is not an admission that anything discussed below is citable as prior art or part of the general knowledge of workers in the field in any country.
Bridges often have supporting structures, for example beams or girders, which span the length of the bridge and support a bridge deck. The bridge deck may include cantilevered portions, which may be called overhangs, which run along the length of the bridge but also extend outwards from the supporting structures generally perpendicular to the length of the bridge. A series of overhang brackets placed along the supporting structure may be used to support an overhanging portion of a deck while it is being built. The overhang brackets extend outwards from the supporting structure and supports the weight of workers, tools, and the overhang materials, for example uncured concrete, until the bridge deck is able to support itself. The overhang brackets are then removed and moved to another work area or stored for reuse later.
Overhang brackets may have three primary members. These members may be called a top, a side and a diagonal member. The three members may be bolted together, for example near their ends, to create a generally right angled triangle. To use an overhang bracket, a tie rod is attached between the supporting structure and the top member to hang the overhang bracket from the supporting structure. The proximal ends, relative to the supporting structure, of the top and diagonal members abut against the supporting structure. After several such brackets are placed along the supporting structure, joists, beams, or parts of formwork are laid across the top members to provide a shored surface. For example, for a concrete bridge deck, a series of joists may be laid across the overhang brackets along the length of the bridge. Plywood sheets may then be placed over the joists to create the floor and walls of a form, alternately called a mold, for containing newly poured concrete. Metal reinforcing bars, often called rebar, may be laid out over the plywood sheets. Liquid concrete is poured into the form and allowed to harder in place. The mold and overhang brackets may then be stripped and removed from the supporting structure.